diff --git a/Makefile b/Makefile
index 696e080..db732a2 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 SHELL = /bin/sh
 
-# a list of all used commands
+# a list of all used commands (they have to be in your PATH)
 LILYPOND = lilypond
 LUALATEX = lualatex
 MAKEINDEX = makeindex
@@ -11,7 +11,7 @@ PSBOOK = psbook
 PSTOPS = pstops
 PSNUP = psnup
 PS2PDF = ps2pdf
-SED = sed # do not use in-place editing for compatibility between different sed versions 
+SED = sed # do not use in-place editing for compatibility between different sed versions
 RM = rm
 MKDIR = mkdir
 CD = cd